PFC is a circuit which is to improve power conversion efficiency. Under this circuit, the ratio of apparent power to real power can be reduced. E.g. Without the PFC, the power factor is around 0.4~0.6, power plant needs to generate more than 2WVA electricity to fulfill 1W usage. Same condition, the power with PFC circuit (power factor is 0.95), the power plant only needs to generate more than 1.06VA electricity. Therefore, choose an active PFC power supply can contribute to energy saving and environmental protection.